Tuning mechanism



Nov. 20, 1945. a ASC'HWARZ TUNING MECHANISM Filed Sept 7, 1942 W (Ittornegs Patented Nov. 20, 1945 TUNING MECHANISM Bertram A. Schwarz, Kokomo, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 7, 1942, Serial No. 457,614

7 Claims. (01. 25020) This invention relates to indexing means and more particularly to means which may be preset and automatically actuated to bring a radioreceiver to different resonant frequencies for receiving different broadcast stations.

The majority of the radio receiving sets which are built at the present time incorporate two means of tuning the receivers to different stations. They have a series of so-called push buttons which upon manual pressure thereon bring the tuning means to a definite preset position. There may be a series of these, depending upon how many stations the manufacturer believes the set owner would like to have permanently set up. There is also provided means for manually tun-'- ing the set to any intermediate tuned position for receiving other stations which are not so conimonly used by the operator. There is also provided of course in these receivers some visual indicating means so that the operator can by glancing at the set ascertain to which station he is listening. In order to provide as simple a com v bination control of this type as possible; it is necessary to disconnect the manual tuning means from the remainder of the tuning drive when the so-called automatic means is actuated and it is also with a view to simplicity that the indicating means or dial be operated by the manual tuning means.

It is therefore an object of my invention to will become apparent as the specification proceeds, my invention will be best understood by reference to the following specification and claims and the illustrations in the accompanying drawing, in which:

Figure 1 is a schematic view showing the syS- tem of resetting the preset tuning means; 7

Figure 2 is an end view of the apparatus shown in Figure 3 taken on line 22 thereof; and

Figure 3 is a plan view showingboth the manresonant circuit. v v

Referring now more specifically to Figure 1, there is shown therein a frame member 2 upon which is rotatably mounted a volume control ual and automatic or preset means for' tuning a knob 4 which is connected by a flexible drive cable 6 with a short rotatable shaft 8 so that when the knob 4 is rotated the shaft 8 will turn] in unison. The shaft 8 is rotatably mounted on a rigid panel I0 which is within the receiver, which panel also carries a variable resistor l2 used to control the volume of the receiver. Carried upon the'rotatable shaft 8 is a slidable sleeve 14 having a slot l6 therein through which a pin shaft 8. Thus the sleeve M will rotate with the shaft, but can at the same time have axial movement with respect thereto; The sleeve I4 is also provided with a circular groove 20 in its outer surface-and a spur gear 22 which is mounted upon the remote end thereof. This spur gearis adapted to mesh with a large gear 24 mounted upon the end of a rotatable shaft 26 to vary the resistancein the volume control I2. 7 I

Pivoted on the frame at 28 is'a lever 30, one end of which is pivotally connected to a' magnetic core 32 which is mounted within a'magnetic coil 34. The opposite end' of the lever'30 carries a small pin 36 which projects down into the circular. groove 20 in the sleeve l4 and tends to move'the sleeve axially as the lever is 'pivoted about its pivot 28 but'permits rotationof the sleeve. A tension-spring 38is connected to one arm of the lever and to astationary point 40on the frame and tends to rotate the lever clockwise about its pivot'and'to withdraw the magnetic core member '32 from the coil 34. The coil 34 is connected by line 42 to a manual push buttonswitch 44, the opposite terminal of which is connected to a source of power 46 and thence to round.

Thus in the normal operation'of the device the knob 4 when rotated'will turn the flexible shaft 6, which in turn rotates theshort shaft 8 to turn is provided a drum type presettable'tuning unit indicated generally at 48 which rotates about the drum axis and has a plurality of axially extendin threaded shafts 50 about its periphery, upon which threaded shafts there are a plurality of displaceable indexing means, the positions of which can be altered by the rotation of said threaded shafts.

This general drum tuner construction is described position of the indexing means will be changed.

Each threaded shaft 50 carries outside the drum. ,0 head a driving gear such as 52, each of which it" is desired to cause to mesh sequentially withltlie; gear 22 when the latter is in its innermost position. Thus as the lever 30 moves'the sljeeye l4' toi' If? the left as shown in Figure 1, it will bring'the gears K 22 and 52 of that particular threaded shaft which is in engageable position into" mesh/ Then-any l rotation of the knob 4 will, instead of causing a volume change, cause a change in the position of the indexing member on that shaft 50 and theie.-.. 0 fore-presetrthe'indexing means to a new position. Thereafter as'the indexing. drum is rotated each: time that particular indexingmeans 'comesinto position; the 'new station will. be received. ,Thus, in order to preset to a new position any .of the au tomatic ,presetindexing means onfthe drum, it. is only necessary to hold the switch 44in closed po sitioniand operate the volume'control means to reset instead of: the manual tuning-means as the automatic .tuningibuttons are depressed. This leaves that portion of the system free to operate the indexing means as desired;

Figure 2='deals primarily with the indicatingmeansrand the manual controlimeans' justmen= tioned inthat again there isi shown the drumtun er .48 :which has spaced'arcuately aroundits peri phery a series of gears 52, each of-which is connected to the end of "a threaded shaft Ell which shafts areparallel to each other andc'arry'indexing lugs '54: Ihese'projecting lugs 'are adapted as they rotate'to come between 'one side of smuate horns 56 and to-move the same sideways oraxia-lly: suchmo'vement causing a direct and equiva lent-movement .of ashaft 58 upon'which the di vergent horns'are mounted. Also secured to the shaft 58 and "at a spaced position is' a tuning means, which,'in'this instance; is illustrated as be ingfia comminutedcore 60 which may be placed at diflerent'posltions:;within a tuning coil'62." Of course this motion 'm'ayequally as well be appliecl toirotati'ng a condenser for tuning if desired. The drum 48 'is' rotated to different positions by a ratchet'64 'which has teeth thereon equal to the number of tuning positions which are provided onthe drum and this ratchet may be operated by any suitable solenoid means not shown, each' actiiation of the same bringing thedrum'toa'iiew tun ing or indexing position; --As"before m'eritir'nie'd. each of the gears 52 controls 'tl'ie"locationof"a presettable index 54' for'automatically tuning in a given station. f f

If it is desired to tune the" set manually; the ratchet solenoid is actuated untilithe drum 'in its" rotation causes'the' lever arm-6'6 to contact one'end of a pivoted lever 68. This lever is mounted upon' a shaft on 'the' opposite side of'the 'sl'idable' horns 56 and is spring biased bya coil spring 12' against a stop 14. On this rotatable lever assembly and forming an integral part thereof is' a hol low tube which carries two'spaced ears l8 and 88 rotatably supporting a threaded shaft 82 near their outer ends. To this threaded shaft is directly secured one end of a flexiblecabledrive" 84, the opposite end of which is connected-toashaft 86 having on the outer end thereof a manwhich engages a stationary rod I 00.

ual knob 88. The shaft 86 also carries a small pulley 90 over which one end of a cord 92 is fed, said cord having clamped thereon an indicator needle 94 which is adapted. to run across the front of the receiver and cooperate with a scale for indicating the position of the tuning means.

The threaded shaft 82 carries an extendin adjustable lug tlfi'similar toithose 'on the-presettable automatic threaded shafts. This lug may be given axial movement by rotation of the threaded shaft portion 82 audit is prevented from turnmg 'entirely around the same by a projection 98 Thus as thefls'olenoid: rotates f the drum 48 to different a'ngularl bs'itionsjth'e lugs 54 will be forced down between the divergent horns and cause the tun- -.ing.5meansito move .to diiferent preselected positions When, however, we reach the point at which the lever 66 engages 68, further movement will-pausejit tOmoveBB. to the dotted line setitorbe tuned manually. Assoon as the ratchet mo es nothe tq t w r. h ver ill. slip o f. he .end of the .lever 68"and it will return; to. its full lineposition .due to the tension ofthe spring 12, and from that point on the automatic,

stations willbe broughtinto engagement with the horns.-

.By this means the manual control will be substantially. independent of'the automatic or push;

buttonecontrol -and .willhave associated there;-

with .an indicator for. showing to which station; the;.- Inanual means. is tuned. Ihe indication not necessary on the automatic stations as theyarepsually labeled as to which station they have been-preset F h n chan e. in..th.e.

'presetting' can be accomplished through the volume control shaft and it is not necessary to diSr.. ur .-thma e r re n w rlclaimt-z.

ntrol system for radio 1 apparatus hav fing tuning -means, a pluralityof presettable indexing, :means to., sequentia1 1y.-; move the; tuning means. to;- .different .predetermined positions;- means to adjust the indexing meansitodiiferentg positions, .vplumercontrol means for the receiver,

shiftable driving means to selectively engage. either the means to adjust the indexingmeans. or the volume control means, and a separate manually rotatable; means to :tune the-receiver over' the range thereof. 'ri- 2. I-nwacontrol system for radio apparatus having tuning= means, a plurality of 'presettable index-ing meansto sequentially move the tuning means to different predetermined positions; means to adjust the indexing-means to different positions; volume control means for the'receivexi" shiftablevdriving means. to selectively-engage either the means; to adjust the indexing means or-thevolume control means, a'separate manu ally rotatable means to tune-.the receiver overi therange-,-thereof and visual. indicatingmeans driven bythe manually rotatable means .to .indicate the position of the tuning means.

3. In acontrol system for radio apparatus haw. ins; tuning means, a rotatable 'drum controller, a -plurality of circumferentiallyspaced threaded i parallel rods carried by said drum-,wadjustablev nut .as semblies oneach whose axialposition may bachangedwbyrotation of'the' rod; means con:-.i; nected to the tuning means tobe sequentially engaged by the nut assemblies as the drum rotates to tune the set to different stations, manually driven means located adjacent the means connected to the tuning means spring biased away from the same and means extending from the drum adapted to engage the manually driven means and move it against its spring bias into engagement with the means connected to the tuning means to provide manual tuning at one point.

4. In a control system for radio apparatus having tuning means, a rotatable drum controller, a plurality of circumferentially spaced threaded parallel rods carried by said drum, adjustable nut assemblies on each whose axial position may be changed by rotation of the rod, means connected to the tuning means to be sequentially engaged by the nut assemblies as the drum rotates to tune the set to different stations, manually driven means located adjacent the means connected to the tuning means spring biased away from the same, means extending from the drum adapted to engage the manually driven means and move it against its spring bias into engagement with the means connected to the tuning means to provide manual tuning at one point, and indicating means connected to and driven by the manually driven means.

5. In a control system for radio apparatus having tuning means, reciprocating means connected to and capable of moving the tuning means, rotatable drum means having adjustable projections at spaced peripheral points to sequentially engage and move the reciprocating means, a second pivoted adjustable projection means also mounted adjacent the reciprocating means and adapted to engage the same for tuning and means on the drum to engage the pivoted means to cause it to move into engagement with the reciprocating means.

6. In a control system for radio apparatus having tuning means, reciprocating means connected to and capable of moving the tuning means, rotatable drum means having adjustable projections at spaced peripheral points to sequentially engage and move the reciprocating means, a second pivoted adjustable projection means also mounted adjacent the reciprocating means and adapted to engage the same for tuning and means on the drum to engage the pivoted means to cause it to move into engagement with the reciprocating means and manual means for adjusting the position of the pivoted projection.

'7. In a control system for a radio set having tuning means, a plurality of presettable indexing members therefor, means for moving the same along a prescribed path, a volume control for the receiver, a manually operable means for operating the volume control, means for disconnecting said manually operable means from the volume control and connecting it to one of the indexing means to alter the position thereof as the same is rotated, and a second separate manually operated indexing means.

BERTRAM A. SCHWARZ. 

